package com.lagou.sqlSession;

import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;

import java.lang.reflect.*;
import java.util.List;

/**
 * @author liuyj
 * @Title: DefaultSqlSession
 * @create 2020-05-28 11:57
 * @ProjectName lagou_project
 * @Description: TODO
 */
public class DefaultSqlSession implements SqlSession {
    private Configuration configuration;

    public DefaultSqlSession(Configuration configuration) {
        this.configuration = configuration;
    }

    public <E> List<E> selectList(String statementid, Object... params) throws Exception {

        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        List<Object> list = simpleExecutor.query(configuration, mappedStatement, params);

        return (List<E>) list;
    }

    public <T> T selectOne(String statementid, Object... params) throws Exception {
        List<Object> objects = selectList(statementid, params);
        if(objects.size()==1){
            return (T) objects.get(0);
        }else {
            throw new RuntimeException("查询结果为空或者返回结果过多");
        }

    }

    @Override
    public <T> T getMapper(Class<?> mapperClass) {
    //使用jdk动态代理来为dao生成代理对象，并返回
        Object newProxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //根据不同情况，来调用selctList或者selectOne
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                // 方法名：findAll
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className+"."+methodName;

                // 准备参数2：params:args
                // 获取被调用方法的返回值类型
                Type genericReturnType = method.getGenericReturnType();
                // 判断是否进行了 泛型类型参数化
                if(genericReturnType instanceof ParameterizedType){
                    List<Object> objects = selectList(statementId, args);
                    return objects;
                }

                return selectOne(statementId,args);

            }
        });

        return (T) newProxyInstance;
    }

    @Override
    public int insertOne(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的insert方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        int flag= simpleExecutor.insertOne(configuration, mappedStatement, params);

        return flag;
    }

    @Override
    public <T> T getInsertOneMapper(Class<?> mapperClass) {
        //使用jdk动态代理来为dao生成代理对象，并返回
        Object newProxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //调用insertOne方法
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                // 方法名：findAll
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className+"."+methodName;

                // 准备参数2：params:args

                return insertOne(statementId,args);

            }
        });

        return (T) newProxyInstance;
    }

    @Override
    public int deleteOne(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的delete方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        int flag= simpleExecutor.deleteOne(configuration, mappedStatement, params);

        return flag;
    }

    @Override
    public <T> T getDeleteOneMapper(Class<?> mapperClass) {
        //使用jdk动态代理来为dao生成代理对象，并返回
        Object newProxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //调用insertOne方法
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                // 方法名：findAll
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className+"."+methodName;

                // 准备参数2：params:args

                return deleteOne(statementId,args);

            }
        });

        return (T) newProxyInstance;
    }

    @Override
    public int updateOne(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的update方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        int flag= simpleExecutor.updateOne(configuration, mappedStatement, params);

        return flag;
    }

    @Override
    public <T> T getUpdateOneMapper(Class<?> mapperClass) {
        //使用jdk动态代理来为dao生成代理对象，并返回
        Object newProxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //调用insertOne方法
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                // 方法名：findAll
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className+"."+methodName;

                // 准备参数2：params:args

                return updateOne(statementId,args);

            }
        });

        return (T) newProxyInstance;
    }
}
